Washing gravel out of perforate well casings



L. A. LAYNE 2,356,769 WASHING GRAVEL OUT OF PERFORATE WELL CASINGS Aug.29, 194-4.

Filed Dec. 4, 1939 3-Sheets-Sheet 1 4/]. L AYNE 4 I .INVE TOR.

MM BY (fun 6. Wm.

A TTORNEYS.

L. A. LAYNE Aug. 29, 1944.

WASHING GRAVEL OUT OF PERFORATE WELL CASINGS Filed Dec. 4, 1939 PatentedAug. 29.1944

WELL CASINGS wasnmG GRAVEL our OF rEaFoaa'rE I Leslie A. Layne, Houston,Tex. Application December 4, 1939, Serial No. 307,467

' 12 Claims.

Theinvention relates to a means and method of washing gravel out ofperforated well casings so as to increase the filter pack area toeliminate the entrance of sand and to reduce the rate of flowat the edgeof the filter pack.

The present invention finds its greatest advantage in that type offormation where very fine sands are encountered because under suchcircumstances it is often found that where a ,strainer or screen of afine enough gaugeto exclude the sandi's used that it is impossible toobtain a suitable production through such a fine screen. On the otherhand, if a coarse enough screen is used ,to obtain production, the finesand will enter the screen and the well becomes sanded up in a veryshort period of time.

The invention also finds its application in existing wells where thecasing is anchored in position by having been cemented in place andperforated, and where the well may have been producing for some time.Under the'secircumstances the sand is usually packed tightly about theoutside of the cement and around the casing so that the well has stoppedproducing. It is impossible to underream a formation of this sortbecause of the presence of the casing andit is therefore one of theobjects of the present invention to wash out the casing and the sandoutside of the casing so as to form a .cavity which can be filled withgranular material which is deposited in the casing and washed outwardlythrough the perforations in the casing.

It is one of the objects of the invention to form a granular filter packon both the inside and outside of a perforated-easing which is anchoredin a well bore.

Another object of the invention is to deposit granular material in aperforated casing in a well bore and to wash a quantity of such granular material outwardly through the perforations in the casing toreplace the sand about the casing.

Another object of theinvention is to agitate or churn a body of granularmaterial in a per-' forated casing in a well bore so as to wash it out-45 vide a method of procedure and the apparatus 50 for forming a doublefilter pack outside of a per- Fig. 2 is aside elevation withtheequipment arranged ready to begin the washing out of the gravel. i

Fig.3 isa vertical section illustrating an in-! termediate step in themethod, wherein the c'av-j ity outside of the casing has been enlargedand almost filled with granular material.

Fig. 4 isya side elevation partly in section,.-

wherein the washing out string has been rev moved and the strainer isabout to be washed in.- to position.

Fig. 5 is aside elevation partly in section showing the filter pack ashaving been completed both inside and outside of the casing and withthe-strainer in position.

In Fig. l the well bore is indicated generally at and has been providedwitha casing 3 which is anchored in the formation by the cement 4.

' Thisj cement is usually pumped downwardly through the casing leaving aportion 5 thereof in the bottom of the casing to exclude foreignmaterial.

The perforations I may have been formed in the casing in any desiredmanner so as to admit;

newly drilled and cased well or it may be a well which has beenproducing for some time. In

either event, the fine sand ill will be closelyad- Jacent the layer llof cement around the outside of the casingand if it is an old well whichis being re-worked the sand III will be closely packed in positionbecause in all probability the well is being reworked because of thefact that the packing of this sand has cut down the production of theoil, gas, or water as the case may be.

forated casing and inside of the casing around a strainertherein. Otherand further objects of the invention will be readily apparent when the.following description is considered in connection with the accompanyingdrawings, wherein:' 4

Fig. 1 is a vertical elevation partly in section,

\ .of the perforated casing anchored in the well bore with the body ofgravel therein.

The upper end of the casing 3 carries acasing head I! and a flow line 13which may be controlled by a valve l4. The casing headl2 has a taperedbowl It in the inner upper end.

A body of granular material I8 is shown as having been deposited insideof the'casing 3 in a sufficient quantity as may have been estimated tobe desirable in forming a suitable filter pack, This body of granularmaterial may have been deposited by shovelling it into the top of thecasing or it may have been deposited hydraulically, or otherwise, and itwill be noted that the granular material is deposited to an elevationabove the uppermost perforations I. v

With the granular material in place the equip ment shown in Fig. 2 willbe installed, which in- .cludes a closure head 20 which may beheld inplace by the bolts 2| and carries a stufiing boxdischargeof liquid inagitating, churning and maintaining a circulation. It is intended thatthis circulation of liquid will agitate the granular material l8 andcause it to be suspended in the flowof liquid so that the liquid willtend to pass outwardly through the perforations I.

Thisliquid discharging from the perforations I will tend to form acavity 30 about the casing 2 by washing away some of the fine sand Iwhich was packed about the casing'as seen in Fig. 1. This sand will bepicked up by the circulating liquid and asthewashing out pipe 24 isgradually advanced by lowering it in the casing some of the liquid willreturn through those perforationswhich have been passed by the bit 21and this returning liquid will carry some-of the fine sand with itupwardly in the well casing to discharge from the flowline l3. Ofcourse, some of the liquid will pass into the porous formation I insomeinstances.

If'desired the cavity '30 may have been partially or wholly formed by awashing operation prior to the introduction of the granular material I 8or due to the fact that the well might have produced considerable sandprior to,the reworking operation which woul have left a cavity about thecasing.

In any event, it is the intention to 'wash' the granular material l8outwardly throu h.the perforations to form a filter pack about theoutside of the casing. This is desirable because of the fact that alarger diameter filter pack may be in this manner provided. The largerdiameter filter pack is of advantage because the velocity of "flow ofthe fiuid being produced is materially less in, a geometric. proportionto a diameter of th bore .filled with the granular material. A

In this manner the entrance of sand iselimlnated by the large filterpack. In this manner a double filter pack is formed, part of which is onthe outside of the casing and part of which remains inside of thecasing.

ably by the circulation of liquid to suspend the.

that the packing of the fine sand restricts the production to such anextent that the well may become unprofitable, while on the other hand ifa sumciently coarse strainer is placed inthe well to obtain a practicalproduction then the entrance of sand occurs through the strainer to sandup the well and require a clean-out job.

If afllter pack is formed as has been described it seems obvious that itwill exclude this fine to be washed into the granular material withinthecasing. This strainer string may be washed into position in anydesired manner but prefergranular material as the strainer advances.

Fig. 5 shows the strainer 40 after having been washed into positionandthe double filter pack in place both on the inside and outside of thecasing.

Under some circumstances the formation may be such. that asufficientfilter pack may be pro-' vided by merely washing out thegranular mate rial to form the filter pack outside of the casing and thegranular material will then bridge over the perforations and thegranular material remaining inside of the casing maybe removed. The wellwill'thus produce through the gravel pack outside of the casing and thefluid thus produced removed from the well in any desired man- '5 Underother circumstances the producing formation may be such that the gravelpack will be be desirable to place a screen or strainer" adjacent Fig.'3 shows the washing out pipe advanced almost to the bottom .of thecasing and the cavity 30 as having been practically filled with granularmaterial so that the washing out'operation is practically complete.

When it is determined that the desired amount oi granular material hasbeen washed out of the pressure is required to maintain the granular.material' inside of the casing in suspension than casing the washingout pipe may be gradually withdrawn while maintaining circulation so asto leave the granular material settled inside of the I casing. This factmay be determined either by the is required when it is being washed outof the tion is the loosening and washing out of the sand .around thecasing and the replacing of this sand with granular material which willin the future filter out the fine sands. This is true because it hasbeen found that where a fine sand is encountered and a strainer of asumciently fine the top of the. filter pack inside of the casingbutabove the perforations. v I I A fourth circumstance may require that thestrainer be arranged within the gravel pack inside of the casing as hasbeen described in detail above. v

These various arrangements will be adopted and used depending uponthecircumstances encountered, which may vary with the volume ofproduction, the fineness and condition of packand the character ofstrainer required. v

Attention is directed to the fact that the circulating of the granularmaterial out through the perforations continues the agitation of thematerial in the cavity 20 outside of the pipe and .that this agitationloosens the sand to assist in its removal and replacement by thegranular material. when the granularmaterial settles or is depositedafter the circulation is reduced or discontinued, it may be desirable insome instances to pack it in position and this may be accomplished byrestricting the discharge through the flow valve l4 so as toapnlypressure to the granular material and force it into any soft spotsor cavities which might be present. This causes ing of the sand, thetype of ,fluid being produced I the granular material to also pack theparticles thereof together more compactly.

. therein so-that the washing out and agitating of gauge to exclude thesand is placed in the well the gravel and the setting of the strainermaybe accomplishedin a single operation. If this proassa'zco cedure isfollowed it may be desirable to have a smaller diameter wash pipeincorporated inside of the strainer to conduct the agitating liquid tothe bottom of the strainer to be discharged from the shoe thereof. j

Broadly, the invention contemplates a method and apparatus for forming afilter pack by washing granular material out through a perforate casinganchored in a well bore. a

What is claimed is:

1. A method of arranging a granular filter about a perforated casingwhich is anchored in a well bore which comprises the steps of depositinga body of granular material within the casing, running a washing outstring into the casing, pumping liquid through said string whilelowering the string into the body of granular material in the casing,agitating or churning the material with the'liquid so that the materialwill be washed out through the perforations in the casing while some ofthe liquid may pass into the formation and some return to the casingthrough those perforations which have been passed by the liquiddischarge, maintaining such circulation of liquid until the cavity hasbeen washed out as indicated by the sand returning to the surface andthe cavity filled with material, withdrawing the washing out pipe whilecirculating to leave material in the casing, and washing a string ofstrainer into the granular material in the casing so as to provide afilter Pack about the strainer in the casing and between the formationand the outside of the casing.

2. A method of forming a filter pack of granue lar material inside andoutside of an anchored perforated casing in a well bore which compriseswashing the well by circulating liquid so as to loosen. sand packedabout the outside of the casing, depositing a body oi granular materialwithin the casing, agitating such material with a liqout through theperforations in the casing into the cavity, and washing a strainer intothe material remaining in the casing so as to provide a double filterabout the strainer.

3. A method of forming a filter pack of granular material inside andoutside of an anchored and carry some of the granular material therewithto form a filter pack both on the inside and the outside of said pipe.

6. A method of excluding sands from wells wherethe sand is too fine tobe excluded by a strainer through which production of oil may be 6 theinside to the outside of the casing through the perforations, depositingsuch material about the pipe as a filter, and discontinuing circulationso as to leave a filter pack of granular material inside of the pipe.

8. A method of providinga filter pack about a perforate pipe anchored ina well bore which comprises circulating a. granular material from theinside to the outside of the casing through the perforations,depositingsuch material about the pipe as a filter, discontinuingcirculation so as to leave a filter pack of granular material inside ofthe pipe, and arranging a strainerpipe closely adjacent the top of theinside filter pack to receive the fluid being produced. 7

9. A method of providing a filter pack about a perforate pipe anchoredin a well bore which comprises circulating a granular material from theinside to the outside of the casing through 40 uid circulation so as towash a portion thereof the perforations, depositing such material aboutthe pipeas a filter. discontinuing circulation so as to leave a filterpack of granular material insidepf the pipe, and arranging a strainerpipe out through the perforations in the casing into the cavity tofurther enlarge the cavity by replacing some of the sand with granularmaterial,

and washing a strainer into the material remaining in the casing soabout the strainer.

4. A method of forming a doublefilter pack of granular material in awell bore having a perforated casing therein which comprises depositinga body of such material inside the casing, washing some of the materialoutwardly through the perforations with an agitating liquid, and washinga strainer into the granular material inside the ca'sing.

5. In the art of reworking existing oil, gas, or water wells where asand has packed about a perforated string of pipe anchored in the wellbore, the steps of depositing a body of granular material in theperforated pipe, agitating the material with a flow of liquid so thatthe fiow will pass outwardly through the perforations as to provide adouble filter closely adjacent the top of the inside filter pack abovethe perforations in the pipe to receive the V fluid being produced.

10. A method of providing a, filter pack about a perforate pipe anchoredin a well bore which comprises circulating a granular material from theinside to the outside of the-casingthrough the perforations, depositingsuch material about the pipe as a filter, discontinuing circulation soas to leave a filter pack of granular material in- 1 side of the pipe,and arranging a strainer pipe inside of the filter pack within thecasing to receive the fluid being produced.

11.- A method of forming a filter pack about a perforate pipe anchoredin a ,well bore which comprises agitating a granular material within tieas a double filter pack on the inside and outsi e or the pipe.

. 2. A method of forming a filter pack about a perforate pipe-anchoredin a well bore which comprises agitating a granular material within thepipe and conveying a portion of the material through the perforations tothe outside of the pipe so as to form a double filter-pack on the insideand outside of the pipe, and packing the deposited material in positionby restricting the return of the conveying liquid so as to apply anadded pressure to the granular material,

